Pharmaceutical compositions containing irbesartan

ABSTRACT

Pharmaceutical compositions containing irbesartan, alone or in combination with a diuretic, providing tablets with a high relative amount of active agent and excellent wetting and disintegration properties.

This application is a continuation of our prior copending applicationSer. No. 09/390,868, filed Sep. 7, 1999 now abandoned, which in turn isa divisional of prior copending application Ser. No. 09/081,685, filedMay 20, 1998, now U.S. Pat. No. 5,994,348, which in turn is acontinuation of prior copending application Ser. No. 08/642,978, filedMay 6, 1996, now abandoned, which in turn is a continuation-in-part ofprior copending application Ser. No. 08/472,618, filed Jun. 7, 1995, nowabandoned.

FIELD OF THE INVENTION

The present invention relates to pharmaceutical compositions containingirbesartan, preferably in the form of a tablet. The present inventionalso relates to tablets prepared from these compositions.

BACKGROUND OF THE INVENTION

Irbesartan,2-n-butyl-4-spirocyclopentane-1-[(2′-(tetrazol-5-yl)biphenyl-4-yl)methyl]-2-imidazolin-5-one,is a potent, long-acting angiotensin II receptor antagonist which isparticularly useful in the treatment of cardiovascular ailments such ashypertension and heart failure. Irbesartan has the following structure:

and is described in Bernhart et al., U.S. Pat. No. 5,270,317,incorporated herein by reference. Preferred pharmaceutical compositionsof this drug contain, as active ingredient(s), irbesartan alone or incombination with a diuretic such as hydrochlorothiazide.

Irbesartan may be administered in dosages containing a substantialquantity of the active agent (e.g., 75-300 mg). Certain physicalproperties of the drug present a challenge in developing formulationssuitable for preparing a tablet having both a substantial quantity ofactive agent and a small enough tablet mass to allow ease of swallowing.

Irbesartan is, for example, a fluffy material, with relatively low bulkand tap densities. These properties make it difficult to formulate alarge amount of the drug into a small tablet with uniformity of weight,hardness, and other desirable tablet properties. In addition, irbesartanhas certain undesirable flow characteristics, for example, is sticky andcan adhere to surfaces such as tablet punch faces and dies, causingproblems in tableting, especially on a high speed tablet press. The lowaqueous solubility of irbesartan also presents a challenge, since, tokeep the tablet mass small, only limited amounts of excipients may beadded to facilitate wetting, disintegration, and ultimately, rapid andcomplete drug release. The addition of a diuretic such ashydrochlorothiazide, which is also a fluffy material exhibiting poorflow and low aqueous solubility, can further contribute to tabletingproblems.

Thus, there is a need in the art for pharmaceutical compositionscontaining irbesartan, alone or in combination with a diuretic, whichhave good properties for tablet formation, and yet which contain a lowmass of excipients so that small, easily swallowed tablets with a highcontent of active agent may be prepared.

SUMMARY OF THE INVENTION

The present invention provides pharmaceutical compositions containingirbesartan, alone or in combination with a diuretic, which (1) have aminimal mass of added excipients, thereby allowing preparation of small,easily swallowed tablets which enhance patient acceptance andcompliance, and yet which (2) have excellent properties for tabletformation, and (3) provide tablets with excellent wetting,disintegration, and ultimately, rapid and complete drug releaseproperties.

In particular, the present invention provides pharmaceuticalcompositions, especially suitable for forming tablets, comprising fromabout 20 to about 70% by weight irbesartan or pharmaceuticallyacceptable salts thereof, and pharmaceutically acceptable excipients,wherein a tablet formed from aid composition has a dissolutionperformance such that about 80% or greater, preferably 85% or greater,of the irbesartan or salts thereof contained in said tablet dissolvewithin 30 minutes. The present compositions optionally also comprisefrom about 2 to about 33% diuretic, wherein the combined amount ofirbesartan and diuretic does not exceed about 85%.

Preferred compositions containing irbesartan comprise, based on a totalof 100% by weight: (a) from about 20 to about 70% (preferably, about50%) irbesartan, (b) from about 1 to about 70% diluent, (c) from about 2to about 20% binder, (d) from about 1 to about 10% disintegrant, (e)from about 0.1 to about 5% antiadherent, and (f) from about 0.2 to about5% lubricant, and, optionally (g) from about 0.2 to about 6% surfactant,and/or (h) up to about 2% (preferably, from about 0.1 to about 1%)coloring agent.

Preferred compositions containing irbesartan and diuretic comprise,based on a total of 100% by weight: (a) from about 20 to about 70%(preferably, about 50%) irbesartan, (b) from about 2 to about 33%diuretic, wherein the combined loading of (a) and (b) does not exceedabout 85%, (c) from about 1 to about 70% diluent, (d) from about 2 toabout 20% binder, (e) from about 1 to about 10% disintegrant, (f) fromabout 0.1 to about 5% antiadherent, and (g) from about 0.2 to about 5%lubricant, and, optionally, (h) up to about 2% (preferably, from about0.1 to about 1%) coloring agent.

The present compositions may contain up to about 70% w/w irbesartan, orup to about 85% w/w irbesartan and diuretic, and yet can be employed inthe reproducible manufacture of tablets on a large scale. The presentcompositions can, for example, be compressed on high speed tabletingequipment (especially, a high speed tablet press) to form tablets whichare uniform in both weight and content and which exhibit desirablephysical properties, including elegant appearance, low friability, andfast disintegration time. Tablets prepared from the present compositionsare capable of releasing the active component(s), by dissolution, in afast and reproducible manner.

Unless otherwise indicated, mention of irbesartan herein also includespharmaceutically acceptable salts thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in further detail as follows. Thecomponents employed in the compositions of the present invention shouldbe pharmaceutically acceptable, particularly as described in theNational Formulary (NF) or United States Pharmacopeia (USP).

The “dissolution performance” of a tablet, as used herein with respectto irbesartan, refers to the weight % of irbesaftan, based on the totalweight of irbesartan contained in the tablet, which dissolves within 30minutes under the following conditions: using a tablet having a totalweight of from 150 to 600 mg and a USP Apparatus 2, placing the tabletin 1000 mL of 0.1 N hydrochloric acid at 37° C., with a paddle speed of50 rpm, and measuring the amount of irbesartan dissolved (especially,using UV at 244 nm or, when hydrochlorothiazide is also present, usingHPLC, wavelength 272 nm) at 30 minutes. (If desired, the progress ofdissolution may also be monitored at various time points.)

The “dissolution performance” of a tablet, as used herein with respectto a diuretic (preferably, hydrochlorothiazide), refers to the weight %of diuretic, based on the total weight of diuretic contained in thetablet, which dissolves within 30 minutes under the conditions describedabove for irbesartan dissolution. The dissolution performance for thediuretic preferably meets the USP dissolution specification for thediuretic (for hydrochlorothiazide, greater than 60% dissolution at 30minutes). The dissolution performance of a tablet containinghydrochlorothiazide is most preferably such that about 90% or greater ofthe hydrochlorothiazide is dissolved at 30 minutes.

The “diuretic” employed in a composition of the present invention may beany suitable diuretic, or combination of two or more diuretics, such ashydrochlorothiazide, bendroflumethiazide, benzthiazide, chlorothiazide,chlorthalidone, cyclothiazide, hydroflumethiazide, methyclothiazide,metolazone, polythiazide, quinethazone, and trichlormethiazide.Preferably, the diuretic is hydrochlorothiazide.

The “diluent” employed in a composition of the present invention may beone or more compounds which are capable of providing bulk to obtain adesired tablet mass. It is desirable to employ the diluent in an amountat the lower end of the weight range for the diluent. Preferred diluentsare inorganic phosphates such as dibasic calcium phosphate; sugars suchas lactose hydrous or lactose anhydrous; and cellulose or cellulosederivatives such as microcrystalline cellulose.

The “binder” employed in a composition of the present invention may beone or more compounds which are capable of facilitating granulation ofthe irbesartan and/or diuretic into larger, denser, and/or morefree-flowing particles. Preferred binders are alginic acid (mostpreferably employed in the range of 2-5% by weight) or sodium alginate(most preferably employed in the range of 2-3% by weight); cellulose orcellulose derivatives such as carboxymethylcellulose sodium (mostpreferably employed in the range of 2-6% by weight), ethylcellulose(most preferably employed in the range of 2-3% by weight), hydroxyethylcellulose (most preferably employed in the range of 2-5% by weight),hydroxypropyl cellulose (most preferably employed in the range of 2-6%by weight), hydroxypropyl methylcellulose (most preferably employed inthe range of 2-5% by weight), or methylcellulose (most preferablyemployed in the range of 2-6% by weight); gelatin (most preferablyemployed in the range of 2-10% by weight); povidone(polyvinylpyrrolidone, i.e., 1-ethenyl-2-pyrrolidinone homopolymer)(e.g., povidone K-30) (most preferably employed in the range of 2-20% byweight); or starch (most preferably employed in the range of 5-20% byweight) or pregelatinized starch (most preferably employed in the rangeof 2-20, such as 5-20% by weight).

The “disintegrant” employed in a composition of the present inventionmay be one or more compounds which are capable of facilitating the breakup of a tablet prepared from the composition when placed in contact withan aqueous medium. Preferred disintegrants are alginic acid (mostpreferably employed in the range of 2-5% by weight) or sodium alginate(most preferably employed in the range of 2.5-10% by weight); celluloseor cellulose derivatives such as carboximethylcellulose sodium (mostpreferably employed in the range of 2-6% by weight), microcrystallinecellulose (most preferably employed in the range of 5⁻-15% by weight),powdered cellulose (most preferably employed in the range of 5-15% byweight), or croscarmellose sodium (cross-linked polymer ofcarboxymethylcellulose sodium) (most preferably employed in the range of2-5% by weight); crospovidone (cross-linked homopolymer ofN-vinyl-2-pyrrolidinone, i.e., cross-linked 1-ethenyl-2-pyrrolidinone)(most preferably employed in the range of 2-5% by weight);pregelatinized starch (most preferably employed in the range of 5-10% byweight), sodium starch glycolate (most preferably employed in the rangeof 2-8% by weight), or starch (most preferably employed in the range of3-15% by weight).

The “antiadherent” employed in a composition of the present inventionmay be one or more compounds which are capable of reducing thestickiness of the formulation, for example, preventing adherence tometal surfaces. Preferred antiadherents are silicon-containing compoundssuch as silicon dioxide (most preferably employed in the range of0.25-5% (such as 0.5-2 or 2.5 to 3.0%) by weight), magnesium trisilicate(most preferably employed in the range of 0.5-2% by weight), or talc(most preferably employed in the range of 1-5% by weight).

The “lubricant” employed in a composition of the present invention maybe one or more compounds which are capable of preventing tabletingproblems, such as those relating to the release of a tablet preparedfrom the composition from the apparatus on which it is formed, forexample, preventing adherence to the face of the upper punch (picking)or lower punch (sticking) of a tableting apparatus. Preferred lubricantsare fatty acids or fatty acid derivatives such as calcium stearate (mostpreferably employed in the range of 0.5-2% by weight), glycerylmonostearate (most preferably employed in the range of 0.5-2% byweight), glyceryl palmitostearate (most preferably employed in the rangeof 0.5-2% by weight), magnesium stearate (most preferably employed inthe range of 0.2-2% by weight), sodium lauryl sulfate (most preferablyemployed in the range of 1-2% by weight), sodium stearyl fumarate (mostpreferably employed in the range of 0.5-2% by weight), zinc stearate(most preferably employed in the range of 0.5-1.5% by weight).or stearicacid (most preferably employed in the range of 1-3% by weight);hydrogenated vegetable oil (most preferably employed in the range of1-5% by weight); polyalkylene glycols such as polyethylene glycol (mostpreferably employed in the range of 1-5% by weight); sodium benzoate(most preferably employed in the range of 2-5% by weight); or talc (mostpreferably employed in the range of 1-5% by weight).

The “surfactant” employed in a composition of the present invention maybe one or more compounds which are capable of improving the wetting ofthe tablets and/or enhancing dissolution. Preferred surfactants aresodium lauryl sulfate (most preferably employed in the range of 0.2-6%by weight), and poly(oxyethylene),poly(oxypropylene) block co-polymerssuch as poloxamers, especially poloxamer 188 (most preferably employedin the range of 1-6% by weight).

The “coloring agent” (or “colorant”) employed in a composition of thepresent invention may be one or more compounds which impart a desiredcolor to a tablet prepared from the composition. Addition of a coloringagent may be used, for example, so that tablets of different potenciesmay be easily distinguished. Preferred coloring agents are ferricoxides, which are universally accepted.

As can be seen from the above, a single compound may perform two or morefunctions. Calculation of weight percent is preferably on the basis ofthe primary function of a compound in a given composition. The presentcompositions preferably consist essentially of, most preferably, consistof the above-described components.

Preferred Composition

Preferred compositions of the present invention contain one or more ofthe following components in the indicated concentration range (% byweight): irbesartan, 20 to 60 (e.g., 25 to 60), such as 30 to 60, mostpreferably, 30 to 50, especially about 50%; diuretic, 2 to 20, mostpreferably 2 to 17, especially 4 to 9%; diluent, I to 70, mostpreferably 1 to 60, especially 1 to 40%; binder, 5 to 20, mostpreferably 5 to 15%; disintegrant, 4 to 8, most preferably about 5%;antiadherent, 0.25 to 5.0% (such as 0.25 to 1.5, most preferably 0.7 to0.8%, for example, when a diuretic is present or 2.5 to 3.0%, forexample, when a diuretic is not present); lubricant, 0.5 to 1.5, mostpreferably about 1%; and surfactant, 1 to 3, most preferably, about 3%.

The following tables recite preferred compositions of the presentinvention which produce tablets of especially high quality and superiorperformance. Table A recites preferred compositions containingirbesartan; Table B recites preferred compositions containing irbesartanin combination with a diuretic.

TABLE A IRBESARTAN Concentration Preferred Ingredient Component Range (%w/w) irbesartan active drug 20-50 lactose hydrous diluent  1-70microcrystalline cellulose diluent  5-20 (e.g., Avicel ® PH 102⁺)pregelatinized starch binder 10-20 (e.g., Starch ® 1500⁺) croscarmellosesodium disintegrant 4-8 (e.g., Ac-Di-Sol ®⁺) poloxamer,* especiallysurfactant 1-6 poloxamer 188 (e.g., Pluronic ® F68⁺) silicon dioxideantiadherent 0.25-5.0  (e.g., Syloid ® 244⁺) (0.25 to 1.5  or,especially,  2.5 to 3.0) magnesium stearate lubricant 0.5-1.5 TOTAL 100*Optional, but preferred, componet. ⁺These exemplary compounds may beused as desired throughout this specification as appropriate. Forexample, Starch ® 1500 may be used as desired wherever pregelatinizedstarch appears in this specification.

In the above compositions of Table A, the combination of magnesiumstearate and silicon dioxide provides a superior lubrication effectwhile minimizing any decline in tablet dissolution performance; theintragranular:extragranular placement ratio of the disintegrantcroscarmellose sodium is superior (e.g., 1:1); and the poloxamersurfactant improves the aqueous granulation of irbesartan (which ishydrophobic), eases the ejection of tablets after compression andaccelerates the dissolution of the irbesartan active agent.

TABLE B IRBESARTAN IN COMBINATION WITH DIURETIC Concentration PreferredIngredient Component Range (% w/w) irbesartan active drug 20-50hydrochlorothiazide diuretic,  2-20* active drug lactose hydrous diluent 1-70 microcrystalline cellulose diluent 10-20 (e.g., Avicel ® PH 102)croscarmellose sodium disintegrant 4-6 (e.g., Ac-Di-Sol ®)pregeletinized starch binder 10-20 (e.g., Starch ® 1500) silicon dioxideantiadherent 0.5-1.0 (e.g., Syloid ® 244) magnesium stearate lubricant0.5-1.5 TOTAL 100 *The concentration of hydrochlorothiazide can varyaccording to the hydrochlorothiazide potency sought in the combinationtablet, which preferably ranges from 6.25 mg to 25 mg per tablet.

The compositions of Tables A and B preferably also contain 0.08 to 0.12%by weight ferric oxide, red and 0.08 to 0.12% by weight ferric oxide,yellow as a colorant.

Methods of Manufacture

Tablets may be prepared from the present compositions by any suitablemethod for forming tablets. Preferably, tablets are prepared from thepresent compositions by a wet granulation process. An exemplary suchmethod comprises the following steps:

(a) preparing an intragranular composition by:

(i) mixing the irbesartan, diuretic (for combined tablets), a portion ofthe diluent (preferably, from about 5 to about 80% by weight of thetotal diluent), a portion of the disintegrant (preferably, from about 50to about 80% by weight of the total disintegrant), the binder, and,optionally, a portion of the antiadherent (preferably, from about 50 toabout 80% by weight of the total antiadherent), to form a powder blendand, optionally, sizing the blend (e.g., milling the blend to break upaggregates);

(ii) re-mixing the blend;

(iii) granulating the blend with a granulating fluid, preferably waterand/or an aqueous solution of the surfactant, to form granules (e.g.,using a high shear mixer/granulator);

(iv) drying the granules (e.g., in an oven or, preferably, in a fluidbed dryer); and

(v) sizing the dried granules (e.g., by milling or screening);

(b) preparing a mixture of the sized granules of step (a)(v) with anextragranular composition by:

(i) mixing the remainder of the diluent, the remainder of thedisintegrant, the antiadherent or the remainder of the antiadherent,and, optionally, the coloring agent, where one or more of these may bepre-blended, sized (e.g., milled to break up aggregates) and re-mixedprior to this step, with the sized granules from step (a)(v) to form agranule blend; and

(ii) mixing the lubricant with the granule blend; and

(c) compressing the mixture from step (b)(ii) to form tablets (forexample, employing a tablet press).

The solid starting materials of the present compositions are preferablyscreened prior to use. The weight ratio of water (preferably, purifiedwater, USP or water for injection,.USP) to solids employed in step(a)(iii) is preferably within the range of from about 0.25:1 to about0.6:1.

The tablets may, optionally, be finished or coated such as by methodsknown in the art.

The tablets prepared from the compositions of the present inventionpreferably contain (per tablet) from about 25 to about 300 mg ofirbesartan, most preferably from about 75 to 300 mg of irbesartan and,for the combined tablets, an additional amount of from about 1 to about25 mg of diuretic, most preferably from about 6.25 to about 25 mg ofhydrochlorothiazide. The total weight of the tablets prepared ispreferably from about 50 to about 600 mg. In addition to tablets, thecompositions of the present invention may be used to prepare beads,granules for dispersion or capsules, the latter, for example, filledwith powder or the aforementioned beads or granules. Methods such asthose well known in the art may be used to prepare these dosage forms.

The compositions and tablets of the present invention may be used totreat or prevent disorders such as those described in U.S. Pat. No.5,270,317, incorporated herein by reference. Such disorders includecardiovascular disorders, for example, hypertension or heart failure,venous insufficiency, as well as glaucoma, diabetic retinopathy, renalinsufficiency and various complaints of the central nervous system. Thepresent compositions or tablets are preferably administered orally, inan effective amount, to a mammalian (especially, human) subject to treator prevent the aforementioned disorders. For human subjects, preferreddosages of from about 75 mg to about 300 mg of irbesartan (alone or incombination with a diuretic) may be administered, for example, 1 to 2times per day.

The following Examples are provided to illustrate preferred embodimentsof the invention, and are not intended to limit the scope of the presentclaims.

EXAMPLE 1 Preparation of Tablets Containing Irbesartan

Tablets containing irbesartan were prepared in three potencies from thecomposition of the present invention described in the following Table 1:(1) 75 mg irbesartan with a total weight of 150 mg per 10 tablet; (2)150 mg irbesartan with a total weight of 300 mg per tablet; and (3) 300mg irbesartan with a total weight of 600 mg per tablet.

TABLE 1 Concentration Ingredient Component (% w/w) INTRAGRANULARirbesartan active drug 50 lactose hydrous, NF diluent 10.25pregelatinized starch, NF binder 15.0 croscarmellose sodium, NFdisintegrant 2.5 poloxamer 188, NF surfactant 3.0 EXTRAGRANULARmicrocrystalline cellulose, NF diluent 15.0 croscarmellose sodium, NFdisintegrant 2.5 silicon dioxide, NF antiadherent 0.75 magnesiumstearate, USP lubricant 1.0 TOTAL 100.00 100.00

Using the above formulation, the tablets were prepared by a wetgranulation process as follows. In this process, the total amount ofwater employed (by weight) was up to 50% of the total solids weight.

The irbesartan, lactose, pregelatinized starch, and a portion (½) of thecroscarmellose sodium were mixed in a mixer. The powder blend preparedwas passed through sizing equipment (cone mill or oscillator), and mixedin a mixer. The poloxamer 188 was dissolved in water (purified, USP orwater for injection, USP) (25% of the weight of total solids), and usedto wet granulate (with the further addition of water in an amount whichwas up to 25% of the weight of total solids as needed) the mixed powder.The granules obtained were dried (tray or fluid bed dryer) until theloss-on-drying (LOD) was 2% or less. The dried granules were passedthrough a screen or milled to obtain the proper size (1 to 3 mm).

The sized granules were mixed with the silicon dioxide, themicrocrystalline cellulose and the remaining croscarmellose sodium in amixer. The blend obtained was then mixed with the magnesium stearate. Bycompressing the mixture using tableting equipment, tablets were preparedfor each potency having the compositions indicated in the followingTable 2.

TABLE 2 75 mg 150 mg 300 mg Potency Potency Potency Ingredient (mg) (mg)(mg) irbesartan 75.00 150.00 300.00 lactose hydrous, NF 15.38 30.7561.50 microcrystalline cellulose, NF 22.50 45.00 90.00 pregelatinizedstarch, NF 22.50 45.00 90.00 croscarmellose sodium, NF  7.50 15.00 30.00poloxamer 188, NF  4.50  9.00 18.00 (or Pluronic F68, NF) silicondioxide, NF  1.12  2.25  4.50 magnesium stearate, USP  1.50  3.00  6.00Tablet Weight 150.00  300.00  600.00 

EXAMPLE 2 Preparation of Tablets Containing Irbesartan: AlternativeFormulation

Tablets were prepared having the composition of the following Table 3 bya method analogous to that of Example 1.

TABLE 3 Amount Ingredient mg/tablet (% w/w) INTRAGRANULAR irbesartan300.0 (50) lactose hydrous, NF 121.5 (20.25) (diluent) povidoneK-30, USP30.0 (5) (binder) croscarmellose sodium 24.0 (4) (disintegrant) PluronicF681 NF 18.0 (3) (poloxamer, surfactant) EXTRAGRANULAR microcrystalline90.0 (15) cellulose, NF (diluent) croscarmellose sodium 6.0 (1)(disintegrant) silicon dioxide, NF 4.5 (0.75) (antiadherent) magnesiumstearate 6 (1) (lubricant) TOTAL WEIGHT 600.00 (100)

EXAMPLE 3 Preparation of Combination Tablets: Irbesartan andHydrochlorothiazide

Tablets containing a combination of irbesartan and hydrochlorothiazidewere prepared in two potencies from the composition of the presentinvention described in the following Table 4: (1) 75 mg irbesartan/12.5mg hydrochlorothiazide with a total weight of 150 mg per tablet; and(2)150 mg irbesartan/12.5 mg hydrochlorothiazide with a total weight of300 mg per tablet.

TABLE 4 Amount Amount (% w/w) (% w/w) in 75 mg/12.5 mg in 150 mg/12.5 mgIngredient Tablets Tablets INTRAGRANULAR irbesartan 50.00 50.00hydrochlorothiazide, USP 8.33 4.17 lactose hydrous NF 4.72 8.88(diluent) pregelatinized starch, NF 15.00 15.00 (binder) croscarmellosesodium, NF 4.00 4.00 (disintegrant) EXTRAGRANULAR microcrystallinecellulose, NF 15.00 15.00 (diluent) croscarmellose sodium, NF 1.00 1.00(disintegrant) silicon dioxide, NF 0.75 0.75 (antiadherent) ferricoxide, NF, red 0.10 0.10 (colorant) ferric oxide, NF, yellow 0.10 0.10(colorant) magnesium stearate, NF 1.00 1.00 (lubricant) TOTAL 100.00100.00

Tablets having the above compositions were prepared using a wetgranulation process as follows. The irbesartan and hydrochlorothiazidedrug substances, the lactose hydrous, the pregelatinized starch, and aportion (⅘ of the total amount) of the croscarmellose sodium wereweighed out and mixed. This powder blend was then milled to break upaggregates of the drug(s). The milled powder blend was then mixed again,followed by granulation with water (in an amount which was about 55% ofthe weight of total solids), in a mixer/granulator. The wet granuleswere then dried in drying equipment (tray or fluid bed dryer) until theLOD was 2% or less, followed by milling of the dried granules.

A color blend was made by mixing the ferric oxides with a portion (⅓ ofthe total amount) of the microcrystalline cellulose, milling the colorblend, then mixing again. The remaining microcrystalline cellulose, theremaining croscarmellose sodium, the color blend, and the silicondioxide were then weighed, screened, and mixed in a mixer with thedried, milled granules. In a final step, the magnesium stearate wasweighed, screened and mixed with the above granule blend. This finalblend was then compressed into tablets using a suitable tablet press.

Tablets Prepared

For the irbesartan/hydrochlorothiazide 75 mg/12.5 mg tablets, the tabletweight was 150 mg and the tablet hardness was 10-14 SCU (Strong CobbUnits). For the 150 mg/12.5 mg potency tablets, the tablet weight was300 mg and the tablet hardness was 14-18 SCU. For both potency, tablets,the friability was less than 0.5%, the disintegration time was under 7minutes, and the coefficient of variation for tablet weight was under2%. In addition, the dissolution of these tablets meets thespecification for irbesartan dissolution of 85% or greater in 30 minutesand easily meets the USP dissolution specification forhydrochlorothiazide of 60% in 30 minutes.

The tablets of this formulation were found to have good stability. Undercertain conditions, hydrochlorothiazide can hydrolyze to form, asby-product products, a free amine degradant and formaldehyde (D.S. Desaiet al., International Journal of Phaxmaceutics, 107(2), 141-47 (1994)).The selection of excipients can impact the stability ofhydrochlorothiazide. The use of pregelatinized starch as a binder in thepresent compositions was found to impart greater stability tohydrochlorothiazide than, for example, povidone (which resulted in theformation of quantities of the free amine degradant). Poloxamer was alsofound to increase the degradation of hydrochlorothiazide, and therefore,while employed as a preferred component in compositions withouthydrochlorothiazide, poloxamer is not a preferred component for theirbesartan/hydrochlorothiazide compositions of the present invention.The aforementioned preferred compositions of the present inventioncontaining irbesartan and hydrochlorothiazide are thus furtheradvantageous since the excipients employed therein minimize or eliminatehydrochlorothiazide degradation.

EXAMPLE 4 Preparation of Combination Tablets: Irbesartan andHydrochlorothiazide: Alternative Formulations

Tablets were prepared having the compositions 4(A), 4(B), 4(C) or 4(D)of the following Table 5 by methods analogous to those of Example 3.

TABLE 5 4 (A) 4 (B) 4 (C) 4 (D) mg per mg per mg per mg per tablettablet tablet tablet Ingredient (% w/w) (% w/w) (% w/w) (% w/w)INTRAGRANULAR irbesartan  75.0  75.0 150.0 150.0 (active drug)  (50) (50)  (50)  (50) hydrochlorothiazide  12.5  12.5  12.5  12.5 (diuretic,active drug)  (8.33)  (8.33)  (4.17)  (4.17) lactose hydrous, NF  2.575 17.575  17.65  47.65 (diluent)  (1.72)  (11.72)  (5.88)  (15.88)pregelatinized starch, NF  22.5 —  45.0 — (binder)  (15)  (15) povidoneK-30, USP —  7.5 —  15.0 (binder)  (5)  (5) croscarmellose sodium  6.0 6.0  12.0  12.0 (disintegrant)  (4)  (4)  (4)  (4) Pluronic F68, NF 4.5  4.5  9.0  9.0 (poloxamer, surfactant)  (3)  (3)  (3)  (3)EXTRAGRANULAR microcrystalline cellulose  22.5  22.5  45.0  45.0 NF(diluent)  (15)  (15)  (15)  (15) croscarmellose sodium  1.5  1.5  3.0 3.0 (disintegrant)  (1)  (1)  (1)  (1) ferric oxide, NF red  0.15  0.15 0.3  0.3 (colorant)  (0.1)  (0.1)  (0.1)  (0.1) ferric oxide, NF yellow 0.15  0.15  0.3  0.3 (colorant)  (0.1)  (0.1)  (0.1)  (0.1) silicondioxide  1.125  1.125  2.25  2.25 (antiadherent)  (0.75)  (0.75)  (0.75) (0.75) magnesium stearate  1.5  1.5  3.0  3.0 (lubricant)  (1)  (1) (1)  (1) TOTAL WEIGHT 150.00 150.00 300.0 300.0 (100) (100) (100) (100)

EXAMPLE 5 Preparation of Tablets Containing Irbesartan

Tablets containing irbesartan were prepared in three potencies from thecomposition of the present invention described in the following Table 6:(1) 75 mg irbesartan with a total weight of 150 mg per tablet; (2) 150mg irbesartan with a total weight of 300 mg per tablet; and (3) 300 mgirbesartan with a total weight of 600 mg per tablet.

TABLE 6 Concentration Ingredient Component (% w/w) INTRAGRANULARirbesartan active drug 50 lactose hydrous, NF diluent 10.25pregelatinized starch, NF binder 15.0 croscarmellose sodium, NFdisintegrant 2.5 poloxamer 188, NF surfactant 3.0 silicon dioxide, NFantiadherent 2.0 EXTRAGRANULAR microcrystalline cellulose, NF diluent13.0 croscarmellose sodium, NF disintegrant 2.5 silicon dioxide, NFantiadherent 0.75 magnesium stearate, USP lubricant 1.0 TOTAL 100.00100.00

Using the above formulation, the tablets were prepared by a wetgranulation process as follows. In this process, the total amount ofwater employed (by weight) was up to 50% of the total solids weight.

The irbesartan, lactose, pregelatinized starch, a portion (½ ) of thecroscarmellose sodium, and a portion (about 73%) of the silicon dioxidewere mixed in a mixer. The powder blend prepared was passed throughsizing equipment (cone mill or oscillator), and mixed in a mixer. Thepoloxamer 188 was dissolved in water (purified, USP or water forinjection, USP) (25% of the weight of total solids), and used to wetgranulate (with the further addition of water in an amount which was upto 25% of the weight of total solids as needed) the mixed powder. Thegranules obtained were dried (tray or fluid bed dryer) until theloss-on-drying (LOD) was 2% or less. The dried granules were passedthrough a screen or milled to obtain the proper size (1 to 3 mm).

The sized granules were mixed with the remaining silicon dioxide, themicrocrystalline cellulose and the remaining croscarmellose sodium in amixer. The blend obtained was then mixed with the magnesium stearate. Bycompressing the mixture using tableting equipment, tablets were preparedfor each potency having the compositions indicated in the followingTable 7.

TABLE 7 75 mg 150 mg 300 mg Potency Potency Potency Ingredient (mg) (mg)(mg) irbesartan 75.00 150.00  300.00  lactose hydrous, NF 15.38 30.7561.50 microcrystalline cellulose, NF 19.50 39.00 78.00 pregelatinizedstarch, NF 22.50 45.00 90.00 croscarmellose sodium, NF  7.50 15.00 30.00poloxamer 188, NF  4.50  9.00 18.00 (or Pluronic F68, NF) silicondioxide, NF  4.12  8.25 16.50 magnesium stearate, USP  1.50  3.00  6.00Tablet Weight 150.00  300.00  600.00 

Tablets comprising irbesartan or a pharmaceutically acceptable saltthereof, prepared (such as is described herein) by mixing anextragranular composition with granules comprising an antiadherent(preferably, silicon dioxide), may dissolve more rapidly and/orcompletely, and thus may exhibit an improved dissolution performance.

EXAMPLE 6 Preparation of Tablets Containing Irbesartan: AlternativeFormulation

Tablets were prepared having the composition of the following Table 8 bya method analogous to that of Example 5.

TABLE 8 Amount Ingredient mg/tablet (% w/w) INTRAGRANULAR irbesartan300.0 (50) lactose hydrous, NF 121.5 (20.25) (diluent) povidone K-30,USP 30.0 (5) (binder) croscarmellose sodium 24.0 (4) (disintegrant)Pluronic F68, NF 18.0 (3) (poloxamer, surfactant) silicon dioxide, NF12.0 (2) (antiadherent) EXTRAGRANULAR microcrystalline cellulose, NF78.0 (13) (diluent) croscarmellose sodium 6.0 (1) (disintegrant) silicondioxide, NF 4.5 (0.75) (antiadherent) magnesium stearate 6 (1)(lubricant) TOTAL WEIGHT 600.00 (100)

What is claimed is:
 1. A pharmaceutical composition, wherein saidcomposition comprises, based on weight: (a) from about 20 to about 70%irbesartan or a pharmaceutically acceptable salt thereof, (b) from about1 to about 70% diluent, (c) from about 2 to about 20% binder, (d) fromabout 1 to about 10% disintegrant, (e) from about 0.1 to about 5%antiadherent, (f) from about 0.2 to about 5% lubricant, (g) from about0.2 to about 6% surfactant, and optionally (h) up to about 2% coloringagent wherein said diluent is lactose hydrous and microcrystallinecellulose; said binder is pregelatinized starch or povidone; saiddisintegrant is croscarmellose sodium; said antiadherent is silicondioxide; said lubricant is magnesium stearate; and said surfactant ispoloxamer 188; and wherein a tablet formed from said composition has adissolution performance such that about 80% or greater of the irbesartanor salt thereof contained in said tablet dissolves within 30 minutes. 2.The pharmaceutical composition of claim 1, wherein a tablet formed fromsaid composition has a dissolution performance such that about 85% orgreater of the irbesartan or salt thereof contained in said tabletdissolves within 30 minutes.
 3. A pharmaceutical composition of claim 1comprising, based on weight, about 20 to 50% irbesartan; about 1 to 70%diluent; about 10 to 20% binder; about 4 to 8% disintegrant; about 0.25to 5.0% antiadherent; about 0.5 to 1.5% lubricant; and about 1 to 6%surfactant.
 4. A pharmaceutical composition of claim 1, comprising,based on weight, about 50% irbesartan; about 10.25% lactose hydrous;about 15.0% pregelatinized starch; about 5.0% croscarmellose sodium;about 3.0% poloxamer 188; about 15% microcrystalline cellulose; about0.75% silicon dioxide; and about 1.0% magnesium stearate.
 5. Apharmaceutical composition of claim 1, comprising, based on weight,about 50% irbesartan; about 10.25% lactose hydrous; about 15.0%pregelatinized starch; about 5.0% croscarmellose sodium; about 3.0%poloxamer 188; about 13% microcrystalline cellulose; about 2.75% silicondioxide; and about 1.0% magnesium stearate.
 6. A pharmaceuticalcomposition of claim 1, comprising, based on weight, about 50%irbesartan; about 20.25% lactose hydrous; about 5.0% povidone K-30;about 5.0% croscarmellose sodium; about 3.0% poloxamer; about 15%microcrystalline cellulose; about 0.75% silicon dioxide; and about 1.0%magnesium stearate.
 7. A pharmaceutical composition of claim 1,comprising, based on weight, about 50% irbesartan; about 20.25% lactosehydrous; about 5.0% povidone K-30; about 5.0% croscarmellose sodium;about 3.0% poloxamer; about 13% microcrystalline cellulose; about 2.75%silicon dioxide; and about 1.0% magnesium stearate.
 8. A tablet formedfrom the composition of claim
 1. 9. A tablet formed from the compositionof claim
 4. 10. A tablet formed from the composition of claim
 5. 11. Atablet formed from the composition of claim
 6. 12. A tablet formed fromthe composition of claim
 7. 13. A tablet of claim 8, wherein the totalweight of said tablet is from about 50 to about 600 mg.